Oocyte cryopreservation means conservation of oocytes by cold and is commonly known as egg freezing. Vitrification is the cryopreservation technique currently used to preserve oocytes; The oocytes are kept at around -200 o C , in proper equipment and liquid nitrogen; Oocytes preserved by vitrification maintain the characteristics they the date they were collected ; When pregnancy is desired, the oocytes are thawed and used in in vitro fertilization , after which the embryos are implanted in the woman uterus. Oocyte cryopreservation can be used in several circumstances, one of which is the desire to preserve fertility when there is the desire to postpone pregnancy . Women who intend to undergo oocyte cryopreservation for fertility preservation must follow several steps. There is no age limit, but the sooner the better (up to 38 years is the ideal), as the later the lower the chance of pregnancy; There is also no ideal number, but it is assumed that for every 10 oocytes stored, 1 to 2 embryos can be generated. 1 st Follow up with an infertility specialist First of all, a woman who wants to preserve her fertility through oocyte cryopreservation needs to be sure that this is the right way for her and that her health is adequate for the procedures needed. For this, the first thing to have a consultation with a specialist in the area , which in Portugal are gynecologists who are subspecialists in reproduction medicine . These are professionals who can clarify doubts and advise on the best option after: Knowing each woman personal and family health history and her motivations; Make an assessment in a gynecological examination; Review the results of various tests. Among the tests requested are those that allow: To determine the ovarian reserve, which are hormonal tests (in the blood) and ultrasound of the ovaries; Screening for infectious diseases such as HIV / AIDS and hepatitis B. 2 nd Ovarian stimulation treatment To obtain the oocytes for cryopreservation, it will be necessary to undergo an ovarian stimulation treatment. This treatment starts on the first day of a menstrual cycle , which coincides with the first day of menstruation and marks the beginning of the follicular phase of a menstrual cycle. The follicular phase is characterized by the growth and development of ovarian follicles and culminates in ovulation, most commonly of a single follicle. The ovarian stimulation treatment is carried out so that several follicles simultaneously reach the state of development prior to ovulation , that is, the phase in which they are collected for conservation, thus increasing the number of follicles collected in the same procedure. In this way, the probability of success of the treatment and the subsequent use of the oocytes is also enhanced. An ovarian stimulation treatment lasts 10 to 14 days. It includes injections of various drugs to: Promote the growth and development of follicles; Prevent premature ovulation; Promote the synchronized maturation of oocytes. Periodic blood tests and ovarian ultrasounds are performed to monitor treatment results. 3 rd . Collection and cryopreservation of oocytes The ovarian stimulation treatment is followed by the oocytes retrieval. This procedure is performed vaginally under sedation ; To collect the oocytes, a special needle is used connected to an aspiration device, whose movements are guided by ultrasound; On average, the procedure does not last longer than half an hour; There is no need for hospitalization , discharge is given after a period that allows complete recovery from sedation. The oocytes go to the laboratory where they are prepared for the vitrification process. After 24-48 hours the woman can resume her normal daily activities. Risks and complications of oocyte cryopreservation As with any treatment or medical procedure, there are also risks and complications that although not frequent must be known, including: Symptoms associated with ovarian hyperstimulation syndrome, which can be a side effect of some medications used to treat ovarian stimulation; Problems related to the oocytes retrieval, such as lesions to neighboring organs (bladder, uterus, bowel, among others), hemorrhage, infections, which occur in less than 0.1% of cases; Oocyte cryopreservation is not an absolute guaranty of a future pregnancy. The survival rate of oocytes cryopreserved by vitrification is higher than 95%, but many other factors can affect the success of the pregnancy success of the pregnancy like those associated with in vitro fertilization procedures, uterine implantation and, of course, the particularities of each woman and, on the male side, issues associated with sperm. Hospital da Luz do not carry out medically assisted reproduction. However, we have specialists in gynecology / reproduction medicine highly qualified to answer all questions, carry out the necessary medical assessments and advise on what each woman should consider in her choices on this subject. Author: Miguel Tuna Meet the obstetrics-gynecology clinical team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
